Littérature scientifique sur le sujet « Late spring frost »
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Articles de revues sur le sujet "Late spring frost"
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Graczyk, Dariusz, et Małgorzata Szwed. « Changes in the Occurrence of Late Spring Frost in Poland ». Agronomy 10, no 11 (22 novembre 2020) : 1835. http://dx.doi.org/10.3390/agronomy10111835.
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Trends in the appearance of the last spring frost for three thresholds of minimum daily air temperature at the height of 2 m and near the ground were examined for six meteorological stations located in two agricultural regions in Poland. For most time series, the last spring frost, calculated as a consecutive day of the year, showed a statistically significant trend indicating its earlier appearance from 1.6 to about 3.5 days per decade. The date of the last spring frost was also calculated in relation to the ongoing growing season. In this case, few statistically significant changes in the dates of the last frosts were found. The probability of the last spring frost on a specific day of the calendar year and the day of the growing season was also examined for two periods: 1961–1990 and 1991–2020. For low probability levels corresponding to the early dates of the last spring frost, the last frost usually occurred much earlier (6–14 days) in 1991–2020. With the probability levels of 80–90% describing the late occurrence of the last frost with a frequency of once every 5–10 years, at some stations, the last spring frosts occurred at a similar time for both periods.
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Nienstaedt, Hans. « Inheritance and correlations of frost injury, growth, flowering, and cone characteristics in white spruce, Piceaglauca (Moench) Voss ». Canadian Journal of Forest Research 15, no 3 (1 juin 1985) : 498–504. http://dx.doi.org/10.1139/x85-082.
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White spruce progenies from the Lake States (61) and from the Ottawa River Valley, Ontario (31), were tested in north-central Wisconsin. Transplants were raised in nurseries in Wisconsin and Ontario and planted in 1969 in an open field after thorough weed control. Observations in the Wisconsin nursery and in the field between 1971 and 1979 are reported. They included heights, frost damage, spring vegetative growth phenology, strobili production, and three cone characteristics. The discussion concentrates on the relationships between heights and the other measured characteristics. Frost damage proved difficult to assess. In the year of frost, damage is severe, a 50% growth reduction, and the fastest growing trees are most severely damaged. However, in environments with only occasional late spring frosts, permanent damage is negligible. Spring growth initiation was not correlated significantly with total height growth or frost damage. Breeding of late-flushing genotypes that can avoid frost damage is questionable in spite of the high heritability for flushing. Female strobili production was substantial at age 10 years, male production was not. Even so, generation turnovers of 10–15 years may be possible. The impact of fecundity on growth potential is discussed as it relates to multigeneration breeding.
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Tadić, Vjekoslav, Kosta Gligorević, Zoran Mileusnić, Rajko Miodragović, Marko Hajmiler et Dorijan Radočaj. « Agricultural Engineering Technologies in the Control of Frost Damage in Permanent Plantations ». AgriEngineering 5, no 4 (6 novembre 2023) : 2079–111. http://dx.doi.org/10.3390/agriengineering5040128.
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The occurrence of late spring frosts due to climate change causes great damage to plantation production worldwide. The main objective of the paper is to provide a comprehensive overview of the problem and to outline effective protective measures against late spring frosts. The nature of frost depends on regional, altitudinal, and geographic differences, but they all share a common problem: they remove heat, resulting in the freezing of new plant growth and flowers. Tissue freezing is affected by critical temperatures and the frost type, intensity, and duration. Protection against late spring frosts can be broadly divided into three categories: active, passive, and chemical measures. In the field of agricultural engineering, various techniques have been thoroughly researched, and their effectiveness has been confirmed by research. These include various sprinkler systems, different heating devices, and large-diameter fans. Conclusive findings are being made on the performance of these systems in sub-zero temperatures and their cost-effectiveness. Climate change increases the importance of protecting permanent crops from late spring frosts and requires advances in agricultural technology to meet changing production demands and challenges.
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Cutforth, Herb, EG (Ted) O’Brien, Jason Tuchelt et Rick Rickwood. « Long-term changes in the frost-free season on the Canadian prairies ». Canadian Journal of Plant Science 84, no 4 (1 octobre 2004) : 1085–91. http://dx.doi.org/10.4141/p03-169.
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The climate of the prairies has warmed over the past century, especially during late winter and early spring. Some regions of the prairies have warmed faster than others. Climate change has been documented to affect living systems in North America, such as promoting earlier phenological development and longer growing seasons. We examined weather records gathered at several long-term weather-recording sites across the agricultural regions of the Canadian prairies for evidence of trends in last spring frosts, first fall frosts, and frost-free durations. During the latter half of the 20th century, the trends were towards earlier last spring frost dates and towards longer frost-free seasons in the agricultural regions of the Canadian prairies. Across most of the prairies the trends towards later first fall frost dates were smaller and generally not significant. The largest changes have occurred in the central and northern agricultural regions of Alberta, whereas the least change occurred over much of southern Alberta and in southern Manitoba. Key words: Last spring and first fall frost dates, frost-free season, agroclimatic indices, climate change, Canadian prairies
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Imfeld, Noemi, Koen Hufkens et Stefan Brönnimann. « Extreme springs in Switzerland since 1763 in climate and phenological indices ». Climate of the Past 20, no 3 (22 mars 2024) : 659–82. http://dx.doi.org/10.5194/cp-20-659-2024.
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Abstract. Historical sources report manifold on hazardous past climate and weather events that had considerable impacts on society. Studying changes in the occurrence or mechanisms behind such events is, however, hampered by a lack of spatially and temporally complete weather data. In particular, the spring season has received less attention in comparison to summer and winter but is nevertheless relevant, since weather conditions in spring can delay vegetation and create substantial damage due to late-frost events. For Switzerland, we created a daily high-resolution (1 × 1 km2) reconstruction of temperature and precipitation fields from 1763 to 1960 that forms, together with present-day meteorological fields, a 258-year-long gridded data set. With this data set, we study changes in long-term climate and historical weather events based on climate and phenological indices focusing on the spring season. Climate and phenological indices show few changes in the mean during the first 200 years compared to the most recent period from 1991 to 2020, where climate change signals clearly emerged in many indices. We evaluate the climate and phenological indices for three cases of extreme spring weather conditions: an unusually warm spring, two late-frost events, and three cold springs. Warm springs are much more frequent in the 21st century, but a very warm and early spring also occurred in 1862. Spring temperatures, however, do not agree on how anomalously warm the spring was when comparing the Swiss temperature reconstruction with reanalyses that extend back to 1868. The three springs of 1785, 1837, and 1853 were particularly cold, with historical sources reporting, for example, prolonged lake freezing and abundant snowfall. Whereas the springs of 1837 and 1853 were characterized by cold and wet conditions, in the spring of 1785 wet days were below average, and frost days reached an all-time maximum, in particular in the Swiss Plateau, indicating inversion conditions. Such conditions are in line with a high occurrence of northeasterly and high-pressure weather types and historical sources describing Bise conditions, a regional wind in the Alpine area related to inversions. Studying such historical events is valuable, since similar atmospheric conditions can lead to cold springs affecting vegetation growth and agricultural production.
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Neuendorff, E. W., et K. D. Patten. « EFFECT OF HEDGING ON FROST TOLERANCE OF `DELITE' RABBITEYE BLUEBERRIES ». HortScience 25, no 9 (septembre 1990) : 1162d—1162. http://dx.doi.org/10.21273/hortsci.25.9.1162d.
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A late spring frost, -2°C on 10 Mar 1989, destroyed all blossoms on `Delite' rabbiteye blueberries. To determine the effect of hedging as a rejuvenation method, six-year-old `Delite' plants were pruned on 26 April 1989. All branches were removed at 46 cm from ground level. Unpruned control plants were approximately 184 cm tall. On 21 Mar 1990 a frost of -2°C occurred. Two days later bud damage was assessed on three wood types: spring-old (SO), spring growth on old, weak wood; spring-new (SN), spring growth on vigorous 1-year-old shoots; and fall (F), postharvest late summer/fall growth. Buds were identified as to their stage of development. Buds formed on both types of spring wood were further developed than those on fall wood. As flower stage advanced frost damage increased. Blossoms on fall growth were most frost tolerant and SN was more hardy than SO. Subsequent yields will be determined and reported.
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Dolnicki, Adam, et Wojciech Kraj. « Dynamics of frost resistance in various provenances of Abies grandis Lindl. » Acta Societatis Botanicorum Poloniae 67, no 1 (2014) : 51–58. http://dx.doi.org/10.5586/asbp.1998.006.
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The frost resistance of one year old needles and shoots of <em>Abies grandis</em> (seven provenances) and <em>Abies alba</em> (one provenance) was determined using Dexter's method since early autumn till late spring (September-May). Material was collected from trees over ten year old, planted in Beskid Sądecki Range near Krynica, 800 m above sea level. In this study it was found, that in early autumn (September) <em>A. grandis</em> develops weaker frost hardiness than <em>Abies alba</em>. In the late autumn and in winter, provenances coming from region II (according to Müller), and especially provenance 12016, are equal in respect to frost hardiness of shoots and needles to <em>Abies alba</em>. Among the provenances from Müller's region I exceptional frost hardiness is displayed by provenance 12005, which is also characterized by fast growth. In spring, <em>Abies alba</em> flushes earlier than <em>A. grandis</em>, which makes it more susceptible to late frosts.
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Čehulić, Ivica, Krunoslav Sever, Ida Katičić Bogdan, Anamarija Jazbec, Željko Škvorc et Saša Bogdan. « Drought Impact on Leaf Phenology and Spring Frost Susceptibility in a Quercus robur L. Provenance Trial ». Forests 10, no 1 (11 janvier 2019) : 50. http://dx.doi.org/10.3390/f10010050.
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Research highlights: The susceptibility of oaks to late spring and early autumn frosts is directly related to their leaf phenology. Drought may alter the leaf phenology and therefore frost tolerance of oaks. However, the effects of drought on oak leaf phenology and frost resistance have not been thoroughly studied. Background and objectives: One of the consequences of climate change is an increase in the frequency of dry episodes during the vegetation period. Pedunculate oak (Quercus robur L.) is an economically and ecologically important forest tree species that prefers humid habitats. Therefore, knowledge of the impact of drought on this species is of great importance for the adaptation of forestry strategies and practices to altered environmental conditions. The aim of this study was to determine the impact of drought on leaf phenology and spring frost susceptibility in nine provenances. Materials and methods: One-year-old saplings originating from nine European provenances were used in the trial. The saplings were exposed to experimental drought and then re-watered in two subsequent years. Spring and autumn leaf phenology were scored. The trial was impacted by a late spring frost in the third year, and the resulting leaf frost injury was scored. The effects of drought treatment on the phenology and frost susceptibility of plants from the provenances were analysed. Results: Leaf phenology of plants from most of the studied provenances was significantly influenced by the drought treatment (p < 0.001). Drought induced a carry-over effect on flushing phenology, which was observed as delayed bud burst (from 0.6 to 2.4 days) in the second year and as advanced bud burst (from 0.1 to 6.3 days) in the third year. Therefore, opposite shifts in flushing phenology may be induced as a result of differences in the time span when plants sense water deficits. In contrast to flushing, autumn leaf phenology was unambiguously delayed following the drought treatments for all studied provenances (from 2.1 to 25.8 days). Differences in late frost susceptibility were predominantly caused by among-provenance differences in flushing phenology. However, the drought treatment significantly increased frost susceptibility in the plants (the rate of frost-injured plants per provenance increased from 3% to 78%). This higher susceptibility to spring frost was most likely caused by the advanced flushing phenology that resulted from the drought treatment in the previous year.
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Zohner, Constantin M., Lidong Mo, Susanne S. Renner, Jens-Christian Svenning, Yann Vitasse, Blas M. Benito, Alejandro Ordonez et al. « Late-spring frost risk between 1959 and 2017 decreased in North America but increased in Europe and Asia ». Proceedings of the National Academy of Sciences 117, no 22 (11 mai 2020) : 12192–200. http://dx.doi.org/10.1073/pnas.1920816117.
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Late-spring frosts (LSFs) affect the performance of plants and animals across the world’s temperate and boreal zones, but despite their ecological and economic impact on agriculture and forestry, the geographic distribution and evolutionary impact of these frost events are poorly understood. Here, we analyze LSFs between 1959 and 2017 and the resistance strategies of Northern Hemisphere woody species to infer trees’ adaptations for minimizing frost damage to their leaves and to forecast forest vulnerability under the ongoing changes in frost frequencies. Trait values on leaf-out and leaf-freezing resistance come from up to 1,500 temperate and boreal woody species cultivated in common gardens. We find that areas in which LSFs are common, such as eastern North America, harbor tree species with cautious (late-leafing) leaf-out strategies. Areas in which LSFs used to be unlikely, such as broad-leaved forests and shrublands in Europe and Asia, instead harbor opportunistic tree species (quickly reacting to warming air temperatures). LSFs in the latter regions are currently increasing, and given species’ innate resistance strategies, we estimate that ∼35% of the European and ∼26% of the Asian temperate forest area, but only ∼10% of the North American, will experience increasing late-frost damage in the future. Our findings reveal region-specific changes in the spring-frost risk that can inform decision-making in land management, forestry, agriculture, and insurance policy.
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Memišević Hodžić, Mirzeta, Almedin Hebibović et Dalibor Ballian. « Phenological variability and resistance to late spring frost of common beech in the international provenance test in Bosnia and Herzegovina ». Acta Silvae et Ligni 126 (décembre 2021) : 11–21. http://dx.doi.org/10.20315/asetl.126.2.
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The research aimed to determine the start, end and duration of leafing phases, the degree of plant damage caused by late spring frost, and the retention of leaves in autumn. The research was conducted in the international common beech provenance test in Bosnia and Herzegovina. The test contains eight provenances from Bosnia and Herzegovina, four from Germany, three from Serbia, two each from Croatia, Romania and Switzerland, and one from Hungary. Leafing phenology, canopy damage caused by late spring frost, and leaf retention were assessed in 2019. Most provenances started opening buds on 17 April 2019. Complete canopy damage affected the highest percentage of plants in provenance BW Bad Wildbad, Germany (68 %), and the lowest in provenance Konjuh Kladanj, Bosnia and Herzegovina (3.2 %). Provenance Herzogenbuchsee from Switzerland had the highest percentage of winter leaf retention (37.5 % of plants). The results can be used in choosing provenances that are resistant to low temperatures in zones of late spring and early autumn frost.
Thèses sur le sujet "Late spring frost"
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Lin, Jianhong. « Ecophysiological modelling of leaf and wood phenology in temperate and boreal forest trees ». Electronic Thesis or Diss., université Paris-Saclay, 2024. http://www.theses.fr/2024UPASB059.
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La phénologie joue un rôle crucial dans le fonctionnement des plantes et les services écosystémiques. La recherche sur la phénologie des arbres est très active, et je me suis attaché dans cette thèse à traiter des questions rarement abordées par la communauté, relatives à la représentation de la variabilité intra-populationnelle de la phénologie, et à la phénologie de formation du bois. À ce jour, la plupart des études phénologiques se sont concentrées sur la phénologie des feuilles à l'échelle des populations, en négligeant les organes non foliaires, tels que le bois et la variabilité entre les individus. Ces lacunes dans les connaissances posent des défis pour prédire avec précision les réponses phénologiques des arbres au changement climatique. Dans cette thèse, j'ai développé le premier modèle phénologique visant à simuler la variabilité intra-populationnelle (WPV) du débourrement dans des populations d'arbres (Chapitre II). Le modèle WPV a été calibré et évalué à l'aide de 48 442 observations de débourrement, collectées entre 2000 et 2022 pour trois espèces d'arbres feuillus tempérés : le charme (Carpinus betulus), le chêne (Quercus petraea) et le châtaignier (Castanea sativa). Les simulations rétrospectives couvrant la période de 1961 à 2022 ont montré un avancement de la date de débourrement en réponse au réchauffement climatique en cours (Chapitre II). De plus, le modèle WPV a été utilisé pour simuler les tendances des dommages causés par les gelées tardives au printemps au cours des six dernières décennies. Les résultats ont montré une diminution générale de la fréquence et de l'ampleur des dommages causés par les gelées tardives dans les populations de chêne à travers la France, en raison de l'avancée plus rapide du dernier gel de printemps par comparaison à l’avancée de la date de débourrement. Il est important de noter que les tendances de la fréquence et de l'ampleur des dommages causés par les gelées tardives au printemps ne sont pas cohérentes (Chapitre III). Au-delà de la phénologie des feuilles, j'ai calibré et validé un modèle de phénologie du bois prédisant la date d’arrêt de l'élargissement des cellules du xylème (cE), en utilisant la base de données GLOBOXYLO, qui documente l'occurrence des stades phénologiques de la formation du bois (Chapitre IV). Cette étude a porté sur trois espèces de conifères de l'hémisphère Nord, à savoir le pin sylvestre (Pinus sylvestris L.), l'épicéa commun (Picea abies Karst) et l'épinette noire (Picea mariana Mill.), totalisant 718 observations de cE sur 130 site-années. Le modèle a montré de bons résultats pour toutes les espèces, avec une erreur quadratique moyenne de 9,2 ± 1,3 jours. Les résultats indiquent que la température et la photopériode jouent un rôle crucial dans la cessation de la croissance des tiges chez l'épicéa commun et l'épinette noire. Cependant, pour le pin sylvestre, seule la température semble avoir une influence significative. De plus, des facteurs ontogénétiques, tels que le nombre total de cellules du cerne, ont également été identifiés comme influençant la cessation de la croissance des tiges pour toutes les espèces de conifères étudiées (Chapitre IV). Enfin, j'ai intégré un modèle complet de la phénologie de formation du bois, incluant un module simulant la reprise printanière de formation du bois (Delpierre et al., 2019) et le modèle de cessation de la phénologie du bois développé dans le Chapitre IV, dans CASTANEA, un modèle mécaniste de fonctionnement des forêts. Les résultats ont révélé des différences significatives dans les prédictions de croissance du bois en fonction de la définition de la période de croissance du bois. Cela souligne l'importance d'incorporer des modèles de phénologie du bois dans les modèles d'écosystèmes terrestres pour utiliser des estimations fiables de la durée de croissance du bois, et améliorer les estimations de biomasse produite et de carbone séquestré par les forêts (Chapitre V)Phenology plays a critical role in plant functioning and ecosystem services, serving as a key indicator of temperate and boreal ecosystems' responses to climate change. Research into tree phenology is very active, and in this thesis, I addressed questions rarely addressed by the community, relating to the representation of intra-population variability in phenology, and the phenology of wood formation. To date, most phenological studies have focused at the population level, primarily on leaf phenology, while largely overlooking the substantial variability among individual trees and the phenology of non-leaf organs, such as wood phenology. These knowledge gaps pose challenges for accurately predicting tree phenological responses to climate change. In this thesis, I developed the first model to simulate the within-population variability (WPV) of budburst in tree populations (Chapter II). The WPV model was calibrated and evaluated using 48,442 budburst observations from 2000 to 2022 in three major temperate deciduous tree species, namely, hornbeam (Carpinus betulus), oak (Quercus petraea) and chestnut (Castanea sativa). Retrospective simulations over the period 1961–2022 showed earlier budburst in response to ongoing climate warming. However, the simulations revealed no significant changes in the duration of budburst (DurBB, i.e., the time interval from BP20 to BP80, representing the dates when 20% and 80% of trees in a population have reached budburst) due to the lack of a significant temperature increase during DurBB (Chapter II). Additionally, the WPV model was used to simulate trends in late spring frost damage over the past six decades. The results showed a general decrease in the frequency and extent of frost damage in oak populations across France, driven by the earlier advancement of the last spring frost compared to budburst under climate change. Notably, the trends for the frequency and extent of late spring frost damage were inconsistent (Chapter III). Beyond leaf phenology, I calibrated and validated a wood phenology model for the cessation of xylem cell enlargement (cE, flagging the cessation of radial stem growth) using the GLOBOXYLO database, which documents the occurrence of wood formation phenological stages (Chapter IV). This study focused on three Northern Hemisphere conifer species, namely Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies Karst) and black spruce (Picea mariana Mill.), including 718 observations of cE across 130 site-years. The model performed well for all species, with a root mean square error of 9.2 ± 1.3 days. The results indicate that both temperature and photoperiod play crucial roles in the cessation of stem growth for Norway spruce and black spruce. However, for Scots pine, only temperature appears to have a significant influence. Additionally, ontogenetic factors, such as the number of radial cells, were also found to influence the cessation of stem growth for all conifer species (Chapter IV). Furthermore, I integrated the wood phenology model, including the chilling-influenced heat sum model for the beginning of wood formation (Delpierre et al., 2019) and the cessation of wood phenology model developed in Chapter IV, into CASTANEA, a mechanistic forest stand model. The results demonstrate significant differences in wood growth predictions depending on the definition of the wood growth period. This underscores the importance of incorporating wood phenology models in terrestrial ecosystem models to obtain reliable estimates of wood growth duration (Chapter V)
Livres sur le sujet "Late spring frost"
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O'Neill, Jennifer. A late spring frost : Circle of friends : just off Main. Waterville, Me : Thorndike Press, 2008.
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Potter, Brian E. A climatology of late-spring freezes in the Northeastern United States. St. Paul, Minn : U.S. Dept. of Agriculture, Forest Service, North Central Research Station, 1999.
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Potter, Brian E. A climatology of late-spring freezes in the Northeastern United States. St. Paul, Minn : U.S. Dept. of Agriculture, Forest Service, North Central Research Station, 1999.
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Potter, Brian E. A climatology of late-spring freezes in the Northeastern United States. St. Paul, Minn : U.S. Dept. of Agriculture, Forest Service, North Central Research Station, 1999.
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A late spring frost. Nashville, Tenn : B & H Pub. Group, 2007.
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O'Neill, Jennifer. A Late Spring Frost (Circle of Friends). B&H Publishing Group, 2007.
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Lambert, Nicholas A. The War Lords and the Gallipoli Disaster. Oxford University Press, 2021. http://dx.doi.org/10.1093/oso/9780197545201.001.0001.
Texte intégralRésumé :
This book offers a new history of an old subject: the genesis of Britain’s disastrous 1915 Dardanelles campaign. It also offers a new history of a new subject—the strategic implications of globalization—because in order to comprehend the former, it is necessary to grasp the latter. Thanks to the development of the international wheat market during the late nineteenth century, the British government came to realize that the national dependence upon imported food had become the Achilles heel of the British Empire. The book shows how the disruption of the global wheat trade during the early months of the First World War exceeded the government’s worst nightmare. By January 1915, the rising price of bread and consequent threat of social unrest required a political response. It came in the form of a seemingly unrelated event: the disastrous British attack at Gallipoli in the spring of 1915. Contrary to all previous narratives which argue this was done for the military–strategic objective of relieving pressure on the Western Front, this books demonstrates that the British government authorized the attack for mainly political–economic reasons: to open the flow of grain from Russia through the Dardanelles in order to bring down the politically dangerous level of bread prices in Britain, and to enable Russia to export wheat and earn foreign exchange that would obviate the need for huge British loans to support its war effort. In so doing, the book offers a case study of grand strategic policymaking under pressure.
Chapitres de livres sur le sujet "Late spring frost"
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Akça, Yasar, et Seyit Mehmet Sen. « Selecting apricots with good fruit quality and resistance to late spring frosts in Gürün ». Dans Developments in Plant Breeding, 177–78. Dordrecht : Springer Netherlands, 1994. http://dx.doi.org/10.1007/978-94-011-0467-8_35.
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Šušteršič, Jakob, Rok Ercegovič, Sandi Drolc et Naser Kabashi. « Polypropylene Fiber Reinforced - Latex Modified Mortar for Installation of Granite Paving Blocks on Various Road Sections ». Dans Springer Proceedings in Materials, 475–84. Cham : Springer Nature Switzerland, 2024. http://dx.doi.org/10.1007/978-3-031-72955-3_48.
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AbstractThe paper discusses the use of Polypropylene Fiber Reinforced - Latex Modified Mortar (PFR-LMM) for installation of granite paving blocks (GPBs) on various road sections in Slovenia. The following four examples are considered: two inner rings of roundabouts on both sides of the bridge over the Sava River on the bypass near Krško, a roundabout in front of the entrance to the Šoštanj thermal power plant and one part of a street in Ljubljana. GPBs were installed on a slab made with Steel Fiber Reinforced Concrete (SFRC). The workability of the fresh PFR-LMM had to be such that it filled the joints between the GPBs. Hardened PFR-LMM, however, must provide a good bond between the GPBs to ensure resistance to traffic loads and resistance to constantly changing weather and temperature influences. The age of the subject applications is between 5 and 11 years.
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Viret, Olivier, et Katia Gindro. « Disease Control ». Dans Science of Fungi in Grapevine, 401–61. Cham : Springer International Publishing, 2024. http://dx.doi.org/10.1007/978-3-031-68663-4_8.
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AbstractFungal disease control in grapevine is essential for the production of high-quality grapes. Regardless of the strategies and modes of production implemented (organic, biodynamic, integrated) and whatever the climatic conditions, growing sensitive Vitis vinifera cultivars depends on the success of disease control. Since the arrival of downy and powdery mildew in Europe over 150 years ago, no alternative to spraying the vines with fungicide at regular intervals has been found. Active ingredients in the fungicides were based on copper and sulphur until the development of newly synthesised molecules in the late 1950s, followed by the release onto the market of several plant protection products. Their regular use raises environmental and human health issues for scientists and practitioners, still searching for more natural and effective alternatives. Despite major research efforts on this front, even naturally occurring molecules used as plant protection products must be applied precisely on the leaves and grape surfaces, requiring the right product, the right dosage and the right timing of the application depending on the biological development of the pathogens and sensitivity of the vine. Success also ultimately depends on the technical performance of the sprayer and its calibration to guarantee efficacy, as well as the protection of the environment and the user.
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Butin, Heinz. « Damage to Buds, Shoots, and Branches ». Dans Tree Diseases And Disorders, sous la direction de David Lonsdale, 76–97. Oxford University PressOxford, 1995. http://dx.doi.org/10.1093/oso/9780198549321.003.0004.
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Abstract Shoots tend to be damaged most severely by frost when it occurs in spring ( ‘late frost ‘), since the tissues are soft at this time and more susceptible to thermal shock than in autumn or winter. However, frosts at the end of the growing season ( ‘early frosts ‘) can also be damaging to certain species that have a continuous flushing habit and set buds late in the summer (e.g. poplars) or not at all (e.g. eucalypts). Severe frost damage causes shoots to wilt and droop, becoming brown and desiccated after a few days. If the damage is sublethal or confined to one side of the shoot, subsequent growth may be stunted, curved, or otherwise distorted, especially in the case of conifers (Fig. 51). In most broadleaved species, the loss of the shoot tips stimulates compensatory growth either from axillary buds (e.g. oak) or from dormant buds (e.g. beech), but this new growth usually bears undersized chlorotic leaves. Conifers are less able than broadleaves to replace lost shoots; an exception to this is larch, which can refoliate entirely.
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Steinberg, Ted. « King Climate in Dixie ». Dans Down To Earth, 71–88. Oxford University PressNew York, NY, 2002. http://dx.doi.org/10.1093/oso/9780195140095.003.0006.
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Abstract April 15, 1849, was one of the strangest spring days on record in Dixie. To the disbelief of many, it snowed. For three hours a blizzard raged across Marietta, Georgia. From the southeastern coast west to Texas, the storm and subsequent frost killed cotton, corn, and other crops, as winter refused to relinquish its grip on the land. “The damage done by the late frost you can hardly form an idea unless you were here to see,” lamented one South Carolina planter. By all measures, the cold spell was an exceptional event, although it seemed to confirm what James Glen, colonial governor of South Carolina, said about a century before: “Our Climate is various and uncertain, to such an extraordinary Degree, that I fear not to affirm, there are no people on Earth, who, I think, can suffer greater extremes of Heat and Cold.”
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Hayes, Kevin J. « The Library of Congress ». Dans The Road TO Monticello, 546–63. Oxford University PressNew York, NY, 2008. http://dx.doi.org/10.1093/oso/9780195307580.003.0037.
Texte intégralRésumé :
Abstract Patrick Magruder, the ailing Librarian of Congress, left Washington in late July 1814 on his physician’s advice to visit the Virginia hot springs in order to recover his health. Before leaving, he put J. T. Frost in charge. Frost, the congressional clerk who acted as assistant librarian, was aided by Samuel Burch, another clerk in the House of Representatives. Unaware of the impending crisis, Magruder did not tell Frost what to do in case of attack. He simply instructed him to air out the books according to regulation. For the sake of the Library of Congress, Magruder chose the worst possible time to take sick leave. Had he stayed in Washington to fulfill his official responsibilities, however, chances are he could have done little more to save the library from destruction than Frost and Burch were able to do.1
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Burt, Stephen, et Tim Burt. « May ». Dans Durham Weather and Climate since 1841, 100–110. Oxford University PressOxford, 2022. http://dx.doi.org/10.1093/oso/9780198870517.003.0008.
Texte intégralRésumé :
Abstract This chapter examines the long-term records (averages and extremes) of temperature, precipitation, sunshine, barometric pressure, wind direction and speed, snowfall, and fog at Durham during the month of May. The chapter includes descriptive accounts and local photographs of notable weather events during the month. As May is a transitional month as regards weather, the chapter covers how, while the month can occasionally exhibit summer-like characteristics, other winter- and late-spring-like weather events (for example, snow, frosty nights, and cooler day temperatures) cannot be ruled out. While May is, on average, the sunniest month in Durham, it is also the second-driest month of the year, after March.
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Officer, Charles, et Jake Page. « The Earth Is Still Hot and Mobile ». Dans Tales of the Earth, 3–31. Oxford University PressNew York, NY, 1993. http://dx.doi.org/10.1093/oso/9780195077858.003.0001.
Texte intégralRésumé :
Abstract People in Maryland knew something was up when the snows of late spring were brown, blue, even red. It was 1816, an unusually cold year. Brown snow fell in Hungary that year, and for the citizens of Taranto in southern Italy, where any snow is unusual, the red and yellow snows that season caused consternation and alarm. The world had gone awry. “During the entire season,” wrote one observer, “the sun arose each morning as though in a cloud of smoke, red and rayless, shedding little light or warmth and setting at night behind a thin cloud of vapor, leaving hardly a trace of its having passed over the face of the Earth.” In New England, 1816 was called “the Year Without a Summer” and also, with Yankee wryness, “Eighteen Hundred and Froze to Death.” As the spring wore on into summer, there were successive cold waves and frosts every month. We know just how cold because the presidents of Yale University during this period-a succession of clergymen and scholars-were willing to rise each morning at 4:30 to read and record the temperature.
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Harward, Grant T. « Epilogue ». Dans Romania's Holy War, 254–68. Cornell University Press, 2021. http://dx.doi.org/10.7591/cornell/9781501759963.003.0010.
Texte intégralRésumé :
This concluding chapter explains how Romania switched sides in late summer 1944 and reluctantly fought alongside the Soviet Union until the end of the war in spring 1945. Romania had delayed negotiating an armistice for as long as possible, in part because the Antonescu regime feared that if it tried, Nazi Germany would occupy the country and replace the government with a Legionary puppet regime, but primarily because most Romanians abhorred the idea of the U.S.S.R. seizing control of their homeland. Indeed, Romania’s alliance with the U.S.S.R. against Nazi Germany proved unpopular. Furthermore, Nazi Germany, while initially cordial regarding the divorce, eventually attempted to attack its erstwhile ally. To conclude, the chapter reflects on Romania’s holy war as well as the nation’s high body count on the eastern front during the Second World War.
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Lambert, Frank. « Growing Up Black in Mississippi ». Dans The Battle of Ole Miss, 13–30. Oxford University PressNew York, NY, 2009. http://dx.doi.org/10.1093/oso/9780195380422.003.0002.
Texte intégralRésumé :
Abstract Moses “Cap” Meredith drove his team of mules up the lane and stopped in front of the farmhouse. He had come for his cows, which had been grazing in the farmer’s field as they had each spring and summer for the past several years. Today was the day that he would pay the farmer for grazing rights, retrieve his cattle, and take them back to his own farm to fatten them for market. Stopping before the walkway that led to the front porch, Cap remained seated and shouted out the farmer’s name to make his presence known. There was no response. Cap knew that the farmer was at home, and, indeed, the man soon appeared at the doorway and hollered for Cap to come around back so they could talk. But Cap did not budge; he continued to sit in stony silence. Minutes stretched into an hour and then into three hours. The farmer was the first to tire of the stand-off, so he emerged from the house, and the two men conducted their business.
Actes de conférences sur le sujet "Late spring frost"
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Malasheva, Petya, Veska Georgieva et Valentin Kazandjiev. « DETERMINATION OF THE HEAT REQUIREMENTS DURING THE ECODORMANCY FOR THE CHERRY (PRUNUS AVIUM) IN BULGARIA ». Dans 23rd SGEM International Multidisciplinary Scientific GeoConference 2023. STEF92 Technology, 2023. http://dx.doi.org/10.5593/sgem2023/4.1/s19.34.
Texte intégralRésumé :
In temperate climates, fruit crop yields are primarily determined by environmental conditions, especially during dormancy and in the early stages of their phenological development. Climate anomalies, with both warmer spring temperatures and greater temperature fluctuation, have altered phenology, leading to a greater risk of spring frost damage to orchards. The sweet cherry (Prunus avium), like other fruit species in the temperate climate, needs to accumulate a cultivar-specific quantity of chilly units during the endodormancy, and heat units during ecodormancy for breaking of dormancy and flowering properly in spring. The knowledge of chilly and heat requirements is important in the selection of the appropriate cultivars for the produces in a particular area. This study aims to estimate growing degree hours (GDH) requirements up to flowering for 12 cherry cultivars grown in the basic regions of industrial cherry production in Bulgaria. Phenological and hourly temperature observations for nine years (2002-2010) were used to perform this study. The GDH were calculated as the sum of temperatures above 5�C accumulated from the breaking of dormancy to the flowering. The heat requirements (HR) for flowering ranged between 1908-3868 GDH. The results indicate that the flowering time of cherry in the studied regions is influenced by GDH. Identification of cultivars with higher HR and later flowering is important for cherry production, especially in regions with frequent late spring frosts occurrence.
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Guo, Yan, Laigang Wang, Jia He, Ting Liu, Yan Zhang et Xiuzhong Yang. « Monitoring and estimation of late spring frost and its impact on winter wheat through multi-temporal GF-1 remotely sensed imagery ». Dans 2021 9th International Conference on Agro-Geoinformatics (Agro-Geoinformatics). IEEE, 2021. http://dx.doi.org/10.1109/agro-geoinformatics50104.2021.9530308.
Texte intégral
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Mircov, Vlad Dragoslav, Adalbert Okros, Casiana Doina Mihut, Anisoara Duma Copcea et Codruta Chis. « INTERPRETATION OF CLIMATE RISK FACTORS FOR THE PERIOD 2019-2022 IN THE WESTERN AREA OF ROMANIA ». Dans 23rd SGEM International Multidisciplinary Scientific GeoConference 2023. STEF92 Technology, 2023. http://dx.doi.org/10.5593/sgem2023/4.1/s19.38.
Texte intégralRésumé :
The purpose of this work is to identify some meteorological risk indicators that most accurately express the extreme nature of the manifestations of atmospheric phenomena in the western part of the country, and for this we analyzed a period of four years, between the years 2019-2022. Most of the basic meteorological parameters of these years were presented for the town of Timisoara, for which we took into account the thermal regime, the pluviometric regime, the atmospheric pressure, the duration of the glow. For the characterization of the wind regime, we used the data provided by other representative weather stations in the Banat area, data provided by the Banat Crisana Regional Meteorological Center and which were analyzed according to multi-year averages. January is the coldest month in the Banat region, as no anomalies are recorded, with average values between 0 and -30C, and spring is somewhat earlier and warmer compared to other areas of the country. Temperature oscillations occur with colder periods under the influence of air masses from the north and northeast, but also warmer periods due to the activity of Mediterranean cyclones. Thus, late frosts and isolated frost can occur in the coldest mornings even at the beginning of May, but also hot days in June. Also in the spring, the first convective manifestations appear with stormy phenomena, torrential rains, hail.
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Malii, Aliona. « Low temperature testing of soybean lines ». Dans Scientific International Symposium “Advanced Biotechnologies - Achievements and Prospects” (VIth Edition), 309–11. Institute of Genetics, Physiology and Plant Protection, 2022. http://dx.doi.org/10.53040/abap6.2022.103.
Texte intégralRésumé :
The experiments were carried out with the aim of testing under climate chamber conditi-ons at low positive temperatures (+4˚С, +8˚С) and the optimal temperature (+25˚С) of soybean lines obtained by experimental mutagenesis (γ rays) to select genotypes capable of germinating under low temperature conditions that are recorded in the Republic of Moldova at the end of march - beginning of april. Climate change in recent years is a global phenomenon with a direct impact on all agri-cultural crops. These climate changes are also felt in the territory of the Republic of Moldova, where the cultivation of spring crops is associated with a high risk due to regular droughts that leave their mark on the production of agricultural crops, leading to important harvest losses or the death of plants. In addition, due to climate warming in recent decades, the frequency, dura-tion and intensity of summer droughts are continuously increasing [1]. In the soybean crop, the most sensitive phase of the ontogenesis is the filling of the grain, which occurs in August - the driest period of the year, which often leads to incomplete filling of the seeds and a noticeable decrease in yield [2]. In order to avoid thermal and water stress conditions in critical moments (flowering, grain filling), technological methods can be used through early sowing and the se-lection of genotypes from groups of lower maturity [3]. Germination and emergence of soybean seedlings of the vast majority of varieties are able to withstand only short-term frosts, up to minus 2 - 4 ˚С. In the Republic of Moldova, soybean sowing is recommended in the second half of April - the beginning of May. One of the ways to increase the profitability of soybeans is to move the sowing dates to earlier and extra early dates (late winter - early spring). This requires varieties resistant to low temperatures, with an active development of plants in early spring against the background of low positive temperatu-res and to survive late spring frosts. An early sowing date for these varieties provides the basis for productivity, as it makes optimal use of the remaining soil moisture from the dry weather winter and allows them to ripen a month earlier than usual, eliminating August droughts [4]. At the same time, early sowing brings a series of advantages to the farmer, limiting their economic risks [5].
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Farahat, Abdallah Magdy, et Domenico Defina. « Novel Adaptive Approach for Applying and Combining Traditional Waterfall and Agile Project Management Methodologies ». Dans ADIPEC. SPE, 2022. http://dx.doi.org/10.2118/210867-ms.
Texte intégralRésumé :
Abstract In modern oil and gas projects, especially in brown field contexts, there are always challenges of working with uncertainties and un-definitions in particular at the late stage of project development. On the other hand, engineering firms need to adapt and implement these changes, in every phase of the development cycle, with high accuracy to reduce delay time and meet client expectations. Hybrid Agile methods ensure that change can be adopted during the development process since they are based on an empirical control model that works through frequent increments, inspections and adaptations. During a brownfield NGL project, EniProgetti Egypt was responsible for detailed design engineering activities to replace traditional cold box heat exchanger with Printed Circuit Heat Exchanger (PCHE). The early phase of the project was characterized by collaborations with involved stakeholders from operations and projects departments in order to define the requirements. Due to the fact that the project was executed in detail engineering following feasibility study neglecting the intermediate front-end engineering design (FEED) phase, there were several criticalities, project un-definitions, risks and uncertainties. This continuous change and uncertainties were a trigger to enable the hybrid agile project management approach, which combines waterfall model and agile. This approach was followed to allow the execution of the engineering design respecting quality standards, meeting deadlines and optimizing the project budget. The paper presents efficient ways to implement and tailor the agile approach in oil and gas projects and how it can be combined with the structured waterfall methodology. The Scrum framework was activated in the early stage of the project development to create the product backlog and categorize requirements and feature stories. Planning was done via Gantt-Agile to outline the devoted deliverable through multiple sprints and monitor performance with S-curve dashboards and burn down charts. The Scrumban with sprint cycles has been applied to each sprint, ending with a review and retrospective meeting to identify lessons learned and improve the remaining sprints. The findings presented in this paper are a novel adaptation of the Agile framework and the predictive methodology for oil and gas projects that determine the important tailor-made process that directly impacts the project success, which in turn helps formulate policies to ensure reliable planning and execution.
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Shephard, Eugene, Nelson Walter, Heath Downey, Peter Collopy et John Conant. « Remediation of Uranium Impacted Sediments in a Watercourse ». Dans ASME 2013 15th International Conference on Environmental Remediation and Radioactive Waste Management. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/icem2013-96115.
Texte intégralRésumé :
In 2009, remediation was initiated for a non-operational fuel cycle facility previously used for government contract work located in Windsor, Connecticut, USA. Radiological contaminants consisted primarily of high enriched uranium (HEU). Other radionuclides encountered in relatively minor amounts in certain areas of the clean-up included Co-60, Cs-137, Ra-226, Th-232 and low enriched uranium (LEU). Between 2009 and the spring of 2011, remediation efforts were focused on demolition of contaminated buildings and removal of contaminated soil. In the late spring of 2011, the last phase of remediation commenced involving the removal of contaminated sediments from portions of a 1,200 meter long gaining stream. Planning and preparation for remediation of the stream began in 2009 with submittal of permit applications to undertake construction activities in a wetland area. The permitting process was lengthy and involved securing permits from multiple agencies. However, early and frequent communication with stakeholders played an integral role in efficiently obtaining the permit approvals. Frequent communication with stakeholders throughout the planning and remediation process also proved to be a key factor in timely completion of the project. The remediation of the stream involved the use of temporary bladder berms to divert surface water flow, water diversion piping, a sediment vacuum removal system, excavation of sediments using small front-end loaders, sediment dewatering, and waste packaging, transportation and disposal. Many safeguards were employed to protect several species of concern in the work area, water management during project activities, challenges encountered during the project, methods of Final Status Survey, and stream restoration.
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Liao, Y. Gene, Brandon Card et John Wasylyk. « COMPARATIVE ANALYSIS OF VIRTUAL AND EXPERIMENTAL PROVING GROUND FOR MEDIUM-DUTY TACTICAL TRUCK USING VARIETY OF SUSPENSIONS ». Dans 2024 NDIA Michigan Chapter Ground Vehicle Systems Engineering and Technology Symposium. 2101 Wilson Blvd, Suite 700, Arlington, VA 22201, United States : National Defense Industrial Association, 2024. http://dx.doi.org/10.4271/2024-01-3618.
Texte intégralRésumé :
<title>ABSTRACT</title> <p>This paper presents the comparative analysis of virtual and experimental proving ground for the performance capabilities of front suspensions in the Family of Medium Tactical Vehicles (FMTV) cargo truck. The front suspension of the current baseline FMTV is a solid axle with leaf springs and shock absorbers. Two other types of suspensions including passive and semi-active suspensions are evaluated in solid and fully independent axle configurations. Virtual proving ground for on- and off-road tests are simulated in the Trucksim environment to include constant radius circular steer, double lane change, sinusoidal steer, washboard road surfaces, and half-round curb strike. Physical proving ground tests are conducted to provide some experimental correlation and validation of the baseline vehicle simulation results. The comprehensive experiments also evaluate the capabilities of various suspensions which have been considered in future FMTV design for mobility performance improvement.</p>
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Solomon, Steven M., Donald F. Forbes, Paul Fraser, Brian Moorman, Christopher W. Stevens et Dustin Whalen. « Nearshore Geohazards in the Southern Beaufort Sea, Canada ». Dans 2008 7th International Pipeline Conference. ASMEDC, 2008. http://dx.doi.org/10.1115/ipc2008-64349.
Texte intégralRésumé :
Proposed development of a gas pipeline southward from the Mackenzie Delta and the presence of known accumulations of gas and oil in the southern Beaufort Sea suggest that construction of pipelines and associated infrastructure in the nearshore are likely to be proposed in the future. Recent surveys undertaken by Natural Resources Canada and its partners have focused on the shallow, poorly mapped nearshore region of the Mackenzie Delta (<6 m water depth) that extends ∼50 km offshore and lies largely within the landfast ice zone. Ice-keel scouring, strudel scour and nearsurface ice-bonding are being investigated. High resolution sidescan sonar and multibeam bathymetry systems were used to map the seabed over three consecutive years and show that ice keel scouring of the seabed is extensive. The maximum scour depth measured was 0.6 m in 6 m water depth with an average scour depth of 0.2 m. The same scours were visible in repeat surveys indicating that sedimentation was sufficiently low during the study, so that the scours were not infilled. Strudel drainage and associated seabed scour occurs when spring-melt river water overflows onto the surface of the landfast and bottomfast ice once discharge exceeds under-ice channel capacity, then drains back through the floating landfast ice via cracks and holes. Although common offshore of small deltas on the Alaska and Yukon coast, these features were first documented in the Mackenzie Delta area during field surveys in 2006 and 2007 that revealed strudel drainage (radial drainage patterns) features on the ice surface. A total of three strudel scours were later identified using swath-survey equipment in 1.2 m of water. The largest scour was 20 m wide with a maximum depth of 0.8 m below the surrounding seabed. Extensive surveys in Alaska have identified strudel scours exceeding 3 m below the seabed. Nearsurface ice-bonding and permafrost are known to occur in shallow water where sea ice freezes to the seabed. A combination of Synthetic Aperture Radar (SAR), ground penetrating radar (GPR) and multi-year ground temperature measurements have been used to map the horizontal and vertical extent of nearsurface ice bonding in extensive shoals found off the front of the Mackenzie Delta. In the shallowest water depths permafrost extends to 22 m below the seabed with an active layer of less than 1.2 m. In deeper water, permafrost disappears but seasonal frost can form in the upper 2–3 m of the seabed.
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Sulaimi, Ghadna, Olanrewaju Oladiran, Fakhriya Shuaibi, Mahmood Hosni, Abdul Malik Kalbani, Suliman Mandhari et Kathiya Alawi. « Agile Field Development Workflow Enabled Fast-Tracking of Clastic Oil Reservoir Maturation : An Agile Early Adopter Success Story, Sultanate of Oman ». Dans ADIPEC. SPE, 2023. http://dx.doi.org/10.2118/216824-ms.
Texte intégralRésumé :
Abstract The newly introduced agile field development process entailed leveraging the use of analogues, to fast-track the Integrated Reservoir Modelling process, provide justification for key project decisions and maximizing the use of existing wells and facility capacity. This paper will describe the workflow which was used to fast track the maturation of oil resources in one of the complex clastic fields in Oman, to move the project from opportunity identification to Final Investment Decision in less than 12 months. Early opportunity scaling through phasing, Front End Loading (FEL) and Integrated Technical Review (ITR) assist was used to structure the assurance requirement for the opportunity maturation and to obtain stakeholder alignment and endorsement for the key select-phase decisions, to enable focus on the remaining key project decisions. Standardization and Replication of existing facility and wells solutions was also applied, such as using existing urban plan as basis for well locations, working with the Asset to identify and secure available hook-up slots for the proposed wells. Agile Project Management Way of Working was also deployed for the first time within a phased maturation process, that involve utilization of in-house task management tool (Injaz), where the tasks were divided into sprints and tracked frequently during regular cadence meetings by the Scrum master. These sprints made the project more flexible and adaptable to changes throughout the maturation cycle. The new Agile Field Development process enabled the team to quickly narrow the decisions solution space and focus on the key select phase decisions (such as build new facility vs. use existing ullage; develop new area now vs. appraise first and develop later), leading to an acceleration of the development schedule by ~2 years. The application of this Agile methodology led to a cost savings of ~ $52mln when compared to normal project maturation workflow. This project is an Early Adopter of Agile Field Development process in the front-end of project Management and is therefore a great model for other projects across the organization to learn from and replicate. The company Agile Project Management Office (PMO) has capitalized on the learnings from this Agile project retrospective and other early successes projects to widely implement Agile Field Development across the portfolio of opportunities.
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Yamaguchi, Daisuke, et Kazuaki Inaba. « Fluid-Structure Interaction in the Nozzle of Collunarium Container ». Dans ASME 2016 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/pvp2016-63792.
Texte intégralRésumé :
Nasal administration of the vaccine is in the spotlight and the medicine has been developed in recent years. The medication is carried out by spraying the medicine in the nasal cavity by collunarium container. The top nozzle part of a common collunarium container consists of three parts, nozzle tip having an exit, cylindrical nozzle, and stepped center rod which is inserted into the nozzle. We confirmed that the spray of collunarium container consists of two stages phenomena (initial jet and its disintegration, and steady spray stage) by visualization with high-speed video camera. Since we found that the initial jet impacted with larger droplet size than later sprayed droplet, we examined the initial jet and steady spray stage in experiments and numerical simulations to study the effect of material and dimension of the rod. The dimensions of the center rod affected the acceleration of the initial jet front and the spray angle in experiments. In numerical simulations including fluid-structure interaction (FSI), lower density rod moved at faster speed and excited higher flow velocity at the exit in the jet stage. Moreover we confirmed that the acceleration of the jet was initiated by the water hammer wave propagation inside the nozzle.